Reserved package:base R Documentation _R_e_s_e_r_v_e_d _W_o_r_d_s _i_n _R _D_e_s_c_r_i_p_t_i_o_n: The reserved words in R's parser are 'if' 'else' 'repeat' 'while' 'function' 'for' 'in' 'next' 'break' 'TRUE' 'FALSE' 'NULL' 'Inf' 'NaN' 'NA' 'NA_integer_' 'NA_real_' 'NA_complex_' 'NA_character_' '...' and '..1', '..2' etc, which are used to refer to arguments passed down from an enclosing function. _D_e_t_a_i_l_s: Reserved words outside quotes are always parsed to be references to the objects linked to in the 'Description', and hence they are not allowed as syntactic names (see 'make.names'). They *are* allowed as non-syntactic names, e.g. inside backtick quotes.